Establishment of the Standard for White Retroreflective Materials Used as Traffic Signs

Abstract

The present paper deals with estimation of various errors for measuring retroreflective materials used for traffic signs, and establishment of their standard. The effect of illuminance distribution on CIL (coefficient of luminous intensity) values was reduced by adopting the average value of illuminance at nine points on the sample surface.
For determination of CIL values, a correction was taken, for slight deviation of spectral sensitivity of the photometer head from spectral luminouss efficiency V (λ), by using a correcting factor calculated from the measurements of spectral reflectance of samples and spectral sensitivity of the photometer head. The errors of sample setting were estimated as 0.3 to-0.1 degrees of arc, and the standard deviation of the CIL value of samples as 0.5 to 0.6%.
Two of the samples took an interlaboratory test among six laboratories for checking industrial standards.